GEELONG has suffered a serious injury blow ahead of Friday night’s preliminary final against the Western Bulldogs with forward Paul Chapman ruled out of the grand final qualifier.

Chapman trained at Skilled Stadium on Tuesday to move a step closer to overcoming the hamstring injury he suffered against St Kilda in the Cats’ qualifying final win earlier this month.

But in the latest injury update released by the Cats on Wednesday morning the 26-year-old's return was listed as one week away.

"There's nothing much to say apart from we've made an early decision that he's not going to be conditioned sufficiently to play on Friday night," football manager Neil Balme said.

"[The injury] is stemming from his whole year really, I suppose, but it is a bit from the St Kilda game, yes.

"We're doing the right thing by him and everyone by saying that we've made a decision, so we thought we might as well tell everyone rather than trying to keep it a secret.

"He's trained this week and will continue to train, [but] it's a decision the club has made that we don't think he's conditioned sufficiently to play the game."

Chapman’s absence is a bonus for Rodney Eade’s Bulldogs, with the nuggety forward having been a thorn in their side in recent meetings.

In his past four matches against the Bulldogs, Chapman has averaged 22 disposals and two goals a game.

Balme maintained no further damage to the muscle had been detected since the qualifying final, but would not be drawn on Chapman's availability should the Cats defeat the Dogs to progress to the grand final.

"There's a big danger of everyone missing a possible Grand Final if we don't win on Friday night," Balme said.